Production method of ultra-pure electronic-grade isopropanol

Abstract

The invention relates to a production method of ultra-pure electronic-grade isopropanol. The electronic-grade isopropanol is obtained by taking industrial-grade isopropanol as a raw material through mixed adsorption water removal, two-stage rectification, metal ion removal, particle removal and continuous purification. The method comprises the following steps: firstly, industrial isopropanol enters an adsorption and water removal process, mixed packing is adopted for temperature swing adsorption, most of water molecules and other impurities in the isopropanol are effectively adsorbed at normal temperature, the moisture content in the dehydrated isopropanol is less than 20ppm, and the dehydrated isopropanol enters a two-stage rectifying tower for continuous rectification and purification; the method comprises the following steps: removing light components and heavy components through light component removal and heavy component removal, extracting qualified components after online component detection, carrying out ion exchange in a mixed loading resin tower, further removing zwitterions, finally filtering through a microporous folded filter element to remove particles, and carrying out secondary dehydration to obtain the G5-grade electronic-grade isopropanol.

Description

Technical Field

[0001] The present invention relates to the field of wet electronic chemicals, and in particular focuses on a method for producing ultra-high purity electronic grade isopropyl alcohol that is efficient, stable and cost-effective. Background Art

[0002] Isopropyl alcohol is an organic compound, an isomer of n-propyl alcohol, also known as dimethyl carbinol and 2-propanol, and also called IPA in the industry. Isopropyl alcohol is an important chemical product and raw material, mainly used in pharmaceuticals, cosmetics, plastics, fragrances, coatings, etc. Electronic grade isopropyl alcohol is a general-purpose solvent electronic chemical. As a cleaning solvent, electronic grade isopropyl alcohol is mainly used to remove surface moisture after wet process cleaning in the wafer and chip industry, TFT-LCD industry, photovoltaic industry, LED industry, etc. Its cleanliness and impurity content have a very important influence on the electrical properties, yield and reliability of integrated circuits. Therefore, it is very important to control the moisture, metal impurities and particle size of electronic grade isopropyl alcohol.

[0003] The existing technology mainly relies on three aspects to control the particle size: At present, the control of particle size mainly relies on three measures: first, through environmental control, provide a suitable ultra-clean environment to meet the production needs of reagents of different levels; second, optimize the process, adopt a continuous and closed production system, reduce the contact between reagents and the outside world, and use ultra-clean polishing equipment and filter materials through precision filter elements; finally, ensure that the finished product is packaged in a clean environment, and the packaging container is ultra-cleaned in advance. These measures can effectively control the particle size by strengthening management and hardware investment.

[0004] However, simple management and hardware investment are often unable to meet the requirements for the control of metal ions and other anions in electronic-grade isopropanol. The production process must be completely optimized. At present, the removal of metal ions mainly adopts two methods: ion exchange and distillation. Although ion exchange can effectively remove metal impurities, the active groups in the ion exchange resin will produce moisture after exchanging with metal ions, resulting in an increase in the moisture content in the solvent, thus affecting the product quality. The distillation method not only consumes a lot of energy, but also has special requirements for equipment materials and is prone to introduce new impurities.

[0005] At present, the removal of metal mainly uses two methods: ion exchange and distillation. The principle of ion exchange is to remove metal impurities by exchanging the active groups on the ion exchange resin with the metal anions and cations in the organic solvent. Most of the active groups in the ion exchange resin are hydrogen ions and hydroxide ions. These two ions combine to generate water, which will increase the moisture content of the solvent. The more metal ions in the solvent, the more water will be generated after ion exchange. The water will remain on the surface of the chip and is difficult to volatilize, causing corrosion on the chip surface. Distillation not only consumes a lot of energy, but also has special requirements for the material of the distillation equipment. General stainless steel materials will lead to an increase in indicators such as iron and chromium, and ordinary glass materials will lead to an increase in indicators such as sodium and silicon. The above methods have their own advantages and disadvantages. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention aims to provide a method for producing ultra-high-purity electronic-grade isopropyl alcohol with low production cost, simple and easy-to-control process and stable product quality. The method uses industrial-grade isopropyl alcohol as raw material, and by breaking through the key technologies of controlling the content of water, metal ions, particle size and organic impurities, the metal ion concentration of electronic-grade isopropyl alcohol is reduced to below 10ppt, while effectively reducing the particle size and water content.

[0007] To achieve the above purpose, the present invention adopts the following process device and production process method: A purification device for electronic grade isopropyl alcohol comprises an industrial grade isopropyl alcohol raw material tank, a primary dehydration tower A, a primary dehydration tower B, a primary buffer tank, a dehydration tower, a dehydration tower, a gas chromatograph, a secondary buffer tank, a resin tower A, a resin tower B, a filter A, a filter B, a secondary dehydration tower A, a secondary dehydration tower B, and a finished product tank; wherein two pipelines are provided below the raw material tank, one is for the tank truck to store incoming materials into the raw material tank, and the other is for the raw material tank to connect the primary dehydration tower; the primary dehydration tower is divided into a primary dehydration tower A and a primary dehydration tower B, one of which is in standby and the other is in use, one of which is dehydrated and restored to performance by using high temperature nitrogen in the process of operation of the other; after the materials come out of the primary dehydration tower, they enter the buffer tank and are then pumped into the dehydration tower, The heavy components are removed, and the components at the top of the heavy removal tower enter the light removal tower to remove the light components. The components at the bottom of the tower enter the secondary buffer tank after being qualified by gas chromatography, otherwise they are sent back to the primary buffer tank for re-refining; the materials in the secondary buffer tank continue to enter the resin tower to remove anions and cations, and the resin tower is divided into resin tower A and resin tower B, one for backup; the materials with anions and cations removed from the resin tower continue to enter the filter, and the filter is divided into filter A and filter B, one for backup; the materials with particles removed from the fine filter continue to enter the secondary dehydration tower for secondary dehydration, and the secondary dehydration tower is divided into secondary dehydration tower A and secondary dehydration tower B, one for backup; the qualified electronic grade isopropyl alcohol finally enters the product tank.

[0008] A production process for ultra-high purity electronic grade isopropyl alcohol comprises the following production steps: (1) Dehydration of mixed packing: Industrial-grade isopropyl alcohol is passed through a mixed packing adsorption tower at a certain flow rate. The packing can remove most of the water in the raw materials; (2) Two-stage distillation: The dehydrated isopropanol enters the deheaving tower (the first distillation tower for primary distillation) and the delightening tower (the second distillation tower for secondary distillation) for cyclic distillation in order to remove volatile components and heavy components such as metal salts by separating light and heavy components; (3) Online purity detection: using a specific detection method to analyze the purity of the material after distillation. When the purity reaches 99.99% or above, proceed to the next step of impurity removal. Otherwise, return it to the buffer tank before the tower and adjust the tower parameters (including but not limited to reflux ratio, feed position, etc.) until the purity of the material after secondary distillation reaches 99.99% or above; (4) Resin filtration: The distilled isopropanol is sent to a resin adsorption tower to further remove anions and cations in the isopropanol through ion exchange; (5) Circulation filtration: The isopropyl alcohol after resin filtration is circulated and filtered to remove nano-sized particles in the isopropyl alcohol.

[0009] (6) Secondary dehydration of mixed filler: Since water will be generated in the process of removing anions and cations, it is necessary to conduct a secondary dehydration and dehydrate it with mixed resin again. The amount of water dehydrated this time is less than the first dehydration and the process is fast, and finally G5 grade electronic grade isopropyl alcohol is obtained.

[0010] In the step (1), the purity of the industrial isopropanol raw material is 99.9%-99.95%, the water content is ≤0.1%, the acetone content is ≤0.01%, and the sulfide content is ≤1ppm; the adsorption dehydration process adopts a mixed adsorbent for adsorption dehydration, one adsorption tower is used and the other is reserved, one adsorption tower is used while the other is regenerated, water molecules in the isopropanol are adsorbed at room temperature, and desorbed at high temperature to obtain regeneration.

[0011] The types of mixed fillers in step (1) are 3A molecular sieve, polyacrylic acid cross-linked resin, and acrylonitrile-vinyl acetate copolymer saponified resin. The filling method is that the upper layer filler is acrylonitrile-vinyl acetate copolymer saponified resin, the middle layer filler is polyacrylic acid cross-linked resin, and the lower layer filler is 3A molecular sieve.

[0012] In some embodiments, the volume ratio of the upper, middle and lower fillers is 1:2-4:3-6, and the diameter ratio of the upper, middle and lower filler beds is 1:1-2:2-4; In some preferred embodiments, the volume ratio of the upper, middle and lower fillers is 1:2:3, and the diameter ratio of the upper, middle and lower filler beds is 1:1:2.

[0013] Using the above conditions, the material is passed through the absorbent material from bottom to top to dehydrate the industrial-grade isopropyl alcohol. The moisture content of the isopropyl alcohol after dehydration can be controlled below 20ppm through moisture detection. This dehydration is to prevent moisture from corroding subsequent pipelines and interfering with the adsorption process.

[0014] During the distillation process of the deweighting tower in step (2), the feed pressure is 3.0-5.0 bar, the feed is at room temperature, the reflux ratio is 13-20, the tower top pressure is 0.05-0.085 MPa, and the tower top extraction ratio is 0.8-1.5; During the distillation process of the light-removal tower, the feed pressure is 2.0-5.0 bar, the feed temperature is 80-85°C, the reflux ratio is 8-15, the tower top pressure is 1.8-3.5 bar, and the tower bottom extraction ratio is 0.7-1.2.

[0015] In step (2), the light component removal process adopts low-pressure steam heating. After the light components in the material are removed, the impurity content of acetone and ether is ≤10ppm; the evaporator, tower, reflux tank and the material contact parts are all made of BA and EP grade stainless steel, and the operating temperature is 85±5℃.

[0016] In step (2), the deweighting process adopts low-pressure steam heating. After removing the heavy components in the material, the content of esters, high boiling points and anionic impurities is ≤1ppm; the evaporator, tower, reflux tank and the material contact parts and pipelines are all made of EP grade stainless steel, and the operating temperature is 85~100℃.

[0017] In some preferred schemes, the feed pressure of the first-stage distillation tower in step (2) is 3.5 bar, the feed is at room temperature, the feed gas-liquid state is liquid phase, the feed position is the 14th tower plate, the theoretical number of plates of the distillation tower is 56, the packing type is theta ring packing, the reflux ratio is 13, the tower top pressure is 0.05-0.085 MPa, the tower top extraction ratio is 0.8, and the first-stage distillation equipment, pipelines and instruments that contact the materials are all mechanically polished with BA grade stainless steel, and the stainless steel material is mechanically or electrolytically polished, with a roughness of ≤0.6um. The feed pressure of the second-stage distillation tower is 2.5 bar, the feed temperature is 80-85℃, the feed gas-liquid state is liquid phase, the feed position is the 35th tower plate, the theoretical number of plates of the distillation tower is 50, the packing type is the West Tower Ring, the reflux ratio is 8, the tower top pressure is 1.8 bar, the tower bottom extraction ratio is 0.81, and the second-stage distillation equipment, pipelines and instruments that contact the materials are all made of EP-grade stainless steel electrolytic polishing, and the stainless steel material is electrolytic polishing with a roughness of ≤0.2um. After the secondary distillation, the isopropanol content reaches 99.99%, of which the anion concentration is controlled below 10ppb and the single cation concentration is controlled below 30ppt.

[0018] In step (3), the purity analysis adopts a chromatographic detection method, and its detection conditions are as follows: chromatographic column: SH-Rtx-624, column temperature program: 40-150°C, 5-10°C / min, split injection, and the organic content of the isopropanol after distillation is detected. When its organic purity reaches 99.99% or more, proceed to the next step.

[0019] In step (4), the removal of anions and cations is carried out by exchange removal using mixed resins, the types of mixed resins are LX318 and ER80, and the filling method is that the upper layer filler is LX318 and the lower layer filler is ER80; When the working pressure of the resin tower is 2-5 bar and the working temperature is 25-30℃, the removal of anions and cations is achieved through the resin cation exchange.

[0020] In some preferred schemes, in step (4), different resins are used for exchange removal of anions and cations. Experiments have shown that the types of mixed resins are LX318 and ER80, and the filling method is that the upper filler is LX318 and the lower filler is ER80. The volume ratio of the upper and lower fillers is 1:3. When the working pressure of the resin tower is 2 bar and the working temperature is 25°C, after the resin cation exchange, the anion concentration in the isopropanol is controlled below 50 ppb, and the single cation concentration is controlled below 30 ppt; however, the water content exceeds 20 ppm, and a dehydration process is required again.

[0021] Step (4) Resin adsorption uses ER80 and LX318 resins. The ion exchange resin itself contains a large number of low-valent ions. When working, the resin has a strong affinity for the high-valent ions in the material, so it will release the low-valent ions inside and adsorb the high-valent ions in the material. The ions inside the cation exchange resin are usually H + Low-valent ions such as OH - Plasma. After adsorption, the anion content in isopropanol is less than 30ppb, and the cation concentration is less than 10ppt, but the moisture content of the material will increase after ion exchange.

[0022] The isopropanol after resin filtration in step (5) is then circulated and filtered, and the filtration is performed in series using microporous folded filter elements with pore sizes of 120-100 nm, 50-40 nm, and 10-5 nm.

[0023] In some preferred schemes, the circulating filtration in step (5) includes three-stage microporous folded filter elements of 100nm, 50nm, and 10nm in series, and each stage of the filter is equipped with a differential pressure gauge for the filter of this stage. When the differential pressure reaches a certain value, the filter element is replaced to ensure the filtration efficiency and product quality. The concentration of particles greater than 0.2 microns in isopropanol after filtration is less than 50 particles / ml, the concentration of particles greater than 0.1 microns is less than 100 particles / ml, and the concentration of particles greater than 0.05 microns is less than 200 particles / ml.

[0024] In step (6), the mixed filler is polyacrylic acid cross-linked resin and acrylonitrile-vinyl acetate copolymer saponified resin, and the filling method is that the upper layer filler is polyacrylic acid cross-linked resin and the lower layer filler is acrylonitrile-vinyl acetate copolymer saponified resin.

[0025] The volume ratio of the upper and lower fillers is 1:2, and the diameter ratio of the upper and lower filler beds is 1:1. In some preferred schemes, the secondary dehydration performed in step (6) is mainly for the water introduced in the ion exchange process, so the water introduced in the process is relatively small, so the mixed filler used is relatively simple compared to the primary dehydration. After the mixed filler is dehydrated, it is detected that the water content of isopropanol after dehydration can also be controlled below 20ppm. This is because the load of this treatment is small and the water removal capacity requirement is not high.

[0026] In summary, the present invention realizes effective control of moisture, metal ions, particle size and organic impurity content in electronic-grade isopropyl alcohol through a series of optimization measures, thereby improving product quality and stability. At the same time, the method has low production cost, simple and easy-to-control process, and provides an efficient and reliable method for preparing electronic-grade isopropyl alcohol for the integrated circuit industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a production process flow chart for ultra-high purity electronic grade isopropyl alcohol.

[0028] Figure 2 This is a structural diagram of the production unit of ultra-high purity electronic grade isopropyl alcohol. In the figure: 1. Industrial grade isopropyl alcohol raw material tank; 2. Primary dehydration tower; 3. Primary dehydration tower B; 4. Primary buffer tank; 5. Light removal tower; 6. Heavy removal tower; 7. Gas phase mass spectrometer; 8. Secondary buffer tank; 9. Resin tower A; 10. Resin tower B; 11. Filter A; 12. Filter B; 13. Secondary dehydration tower; 14. Secondary dehydration tower B; 15. Finished product tank. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the embodiments.

[0030] The analytical instruments for isopropanol in the embodiment include ICP-MS for measuring metal ions, ICS6000 for measuring anions, gas chromatograph for measuring organic content, liquid phase particle counter for measuring particle size and moisture meter for measuring water.

[0031] Example 1 like Figure 2 The purification device of electronic grade isopropyl alcohol shown in the figure includes a raw material tank 1 of industrial grade isopropyl alcohol, a primary dehydration tower A2, a primary dehydration tower B3, a primary buffer tank 4, a heavy removal tower 5, a light removal tower 6, a gas chromatograph 7, a secondary buffer tank 8, a resin tower A9, a resin tower B10, a filter A11, a filter B12, a secondary dehydration tower A13, a secondary dehydration tower B14, and a finished product tank 15; wherein there are two pipelines under the raw material tank 1, one is for the tank truck to store the incoming materials into the raw material tank 1, and the other is for the raw material tank 1 to connect the primary dehydration tower, and the primary dehydration tower is divided into a primary dehydration tower A2 and a primary dehydration tower B 3, one set is in standby mode, one set is in operation and the other set uses high temperature nitrogen to dehydrate and restore performance; after the material comes out of the primary dehydration tower, it enters the buffer tank and is pumped into the de-heavy tower 5 to remove the heavy components, the top components of the de-heavy tower 5 enter the light dehydration tower 6 to remove the light components, and the bottom components enter the secondary buffer tank 8 after being qualified by gas chromatography, otherwise they are returned to the primary buffer tank 4 for re-refining; the material in the secondary buffer tank 8 continues to enter the resin tower to remove anions and cations, wherein the resin tower is divided into resin tower A 9 and resin tower B 10, and the two are in standby mode; the material from which anions and cations are removed by the resin tower continues to enter the filter, wherein the filter is divided into filter A 11 and filter B 12, and the two are in standby mode; the material from which particles are removed by the fine filter continues to enter the secondary dehydration tower 13 for secondary dehydration, and the secondary dehydration tower 13 is divided into secondary dehydration tower A 13 and secondary dehydration tower B 14, and the two are in standby mode; the finally qualified electronic grade isopropyl alcohol enters the product tank 15.

[0032] The primary dehydration tower A2 and the primary dehydration tower B3 are designed to remove a large amount of water in advance to prevent the water from corroding subsequent equipment and preventing the water from affecting distillation and metal removal. The primary dehydration tower adopts a three-layer packing design to remove water in different stages and improve the dehydration efficiency.

[0033] The gas chromatograph is used to detect whether the light and heavy components in the isopropanol after distillation are completely removed (that is, whether the organic purity of the isopropanol reaches 99.99%). If the purity is qualified, it will be sent to the next purification process, which is responsible for re-distillation and impurity removal, and optimization of the distillation process parameters.

[0034] The resin tower adopts a one-in-one-standby design. When one is in use, the other one removes ions to restore its performance.

[0035] The filter adopts a one-on-one-standby design, so when one filter is in use, the other filter removes particles to restore its performance.

[0036] The secondary dehydration tower is used to remove the moisture brought out from the resin tower. Because of its low water content, the dehydration load is relatively small. This secondary dehydration tower adopts a two-layer filler design to remove moisture in different stages and improve dehydration efficiency.

[0037] Example 2 The purification device in Example 1 is used to purify industrial grade isopropanol: After analysis and testing, the impurity contents of the industrial-grade isopropanol to be purified are: The indicators of the electronic isopropanol are: organic purity ≥ 99.99%, moisture ≤ 50ppb, chloride ion ≤ 0.05ppm, particle size: 0.2μm: ≤ 50pcs / mL, 0.1μm: ≤ 100pcs / mL, 0,05μm: ≤ 200pcs / mL. The purification process comprises the following steps: (1) Dehydration of mixed packing: industrial grade isopropyl alcohol is passed through a mixed packing adsorption tower at a certain flow rate. The packing can remove most of the water in the raw material. The types of mixed packing are 3A molecular sieve, polyacrylic acid cross-linked resin, and acrylonitrile-vinyl acetate copolymer saponified resin. The filling method is that the upper layer of packing is acrylonitrile-vinyl acetate copolymer saponified resin, the middle layer of packing is polyacrylic acid cross-linked resin, and the lower layer of packing is 3A molecular sieve. The volume ratio of the upper, middle and lower packing is 1:2:3, and the diameter ratio of the upper, middle and lower packing bed is 1:1:2. Under the above conditions, the material is passed through the water-absorbing material from bottom to top to dehydrate the industrial grade isopropyl alcohol. The moisture content of the isopropyl alcohol after dehydration can be controlled below 20ppm through moisture detection. This dehydration is to prevent moisture from corroding the subsequent pipeline and interfering with the adsorption process.

[0038] (2) Two-stage distillation: the dehydrated isopropanol enters the light-removal tower and the heavy-removal tower in turn for cyclic distillation, and the volatile components and heavy components such as metal salts are removed by separating the light and heavy components; the feed pressure of the first-stage distillation tower is 3.5 bar, the feed is fed at room temperature, the feed gas-liquid state is liquid phase, the feed position is the 14th tower plate, the theoretical number of plates of the distillation tower is 56, the packing type is the West Tower Ring Packing, the reflux ratio is 13, the tower top pressure is 2.5 bar, the tower top extraction ratio is 0.8, the first-stage distillation equipment, pipelines and instruments that contact with the materials are made of stainless steel or fluorine-lined materials, and the BA grade stainless steel material is mechanically polished with a roughness of ≤0.6um. The feed pressure of the second-stage distillation tower is 2.5 bar, the feed temperature is 80-85℃, the feed gas-liquid state is liquid phase, the feed position is the 35th tower plate, the theoretical number of plates of the distillation tower is 50, the packing type is the West Tower Ring, the reflux ratio is 8, the tower top pressure is 1.8 bar, the tower bottom extraction ratio is 0.81, and the second-stage distillation equipment, pipelines and instruments that contact the materials are made of stainless steel or fluorine-lined materials, and the stainless steel material is BA-grade electrolytic polishing with a roughness of ≤0.2um. After the secondary distillation, the isopropanol content reaches 99.99%, of which the anion concentration is controlled below 10ppb and the single cation concentration is controlled below 30ppt.

[0039] (3) Online purity detection: Use a specific detection method (chromatographic column: SH-Rtx-624, column temperature program: 40-150℃, 10℃ / min, split injection) to analyze the purity of the material after distillation. Only when the purity reaches 99.99% or above will the next step of impurity removal be carried out. Otherwise, it will be returned to the buffer tank before the tower and the tower parameters will be adjusted until the purity of the material after secondary distillation reaches 99.99% or above. Use gas chromatography to detect the organic content of isopropanol after distillation. Only when its organic purity reaches 99.99% or above will the next step be carried out.

[0040] (4) Resin filtration: The distilled isopropanol is sent to the resin adsorption tower to further remove the anions and cations in the isopropanol by ion exchange. Different resins are used for exchange and separation of anions and cations. Experiments have shown that the types of mixed resins are LX318 and ER80. The filling method is that the upper layer filler is LX318 and the lower layer filler is ER80. The volume ratio of the upper and lower fillers is 1:3. When the working pressure of the resin tower is 2 bar and the working temperature is 25°C, after the resin cation exchange, the anion concentration in the isopropanol is controlled below 50 ppb, and the single cation concentration is controlled below 30 ppt. However, the water content exceeds 20 ppm, and the dehydration process needs to be carried out again.

[0041] (5) Circulation filtration: The isopropyl alcohol after resin filtration enters the intermediate tank or the finished product tank for circulation filtration to remove nano-sized particles in the isopropyl alcohol. The isopropyl alcohol after resin filtration in step (5) is subjected to circulation filtration. The filtration adopts a microporous folded filter element with a pore size of 100nm, 50nm, and 10nm. The concentration of particles greater than 0.2 microns in the isopropyl alcohol after filtration is 6 particles / ml, the concentration of particles greater than 0.1 microns in the isopropyl alcohol is 45 particles / ml, and the concentration of particles greater than 0.05 microns in the isopropyl alcohol is 61 particles / ml.

[0042] (6) Secondary dehydration of mixed packing: Since water will be generated in the process of removing anions and cations, it is necessary to perform secondary dehydration. The types of mixed packing are polyacrylic acid cross-linked resin and acrylonitrile-vinyl acetate copolymer saponified resin. The filling method is that the upper packing is polyacrylic acid cross-linked resin and the lower packing is acrylonitrile-vinyl acetate copolymer saponified resin. The volume ratio of the upper and lower packings is 1:2, and the diameter ratio of the upper and lower packing beds is 1:1. The above conditions are used to dehydrate industrial-grade isopropyl alcohol. After moisture detection, the moisture content of isopropyl alcohol after dehydration can also be controlled below 20ppm. This is because the load of this treatment is small and the water removal capacity requirement is not high. The dehydration amount is less than the first dehydration and the process is fast, and finally G5 grade electronic-grade isopropyl alcohol is obtained.

[0043] Example 3 The purification device in Example 1 is used to purify industrial-grade isopropanol. In this example, primary dehydration and secondary dehydration are mainly illustrated, and the other steps are consistent with Example 1.

[0044] The types of mixed fillers in the first-stage dehydration tower are 3A molecular sieve, polyacrylic acid cross-linked resin, and acrylonitrile-vinyl acetate copolymer saponified resin. The filling method is that the upper filler is acrylonitrile-vinyl acetate copolymer saponified resin, the middle filler is polyacrylic acid cross-linked resin, and the lower filler is 3A molecular sieve. The volume ratio of the upper, middle and lower fillers is 1:1:3, and the diameter ratio of the upper, middle and lower filler beds is 1:1:2. Using the above conditions, the materials are passed through the water-absorbing material from bottom to top to dehydrate the industrial-grade isopropyl alcohol. The moisture content of the isopropyl alcohol after dehydration can be controlled below 50ppm through moisture detection.

[0045] The types of mixed fillers in the secondary dehydration tower are polyacrylic acid cross-linked resin and acrylonitrile-vinyl acetate copolymer saponified resin. The filling method is that the upper filler is polyacrylic acid cross-linked resin, and the lower filler is acrylonitrile-vinyl acetate copolymer saponified resin. The volume ratio of the upper and lower fillers is 3:2, and the diameter ratio of the upper and lower filler beds is 1:1. The above conditions are used to dehydrate industrial-grade isopropyl alcohol. The moisture content of the isopropyl alcohol after dehydration can also be controlled below 30ppm through moisture detection.

[0046] From this example, it can be seen that the volume ratio of the packing layer is closely related to the water removal rate.

[0047] Example 4 The purification device in Example 1 was used to purify industrial-grade isopropanol. This example mainly illustrates the filler types and operating parameters of the light removal tower and the heavy removal tower, and the other steps are consistent with Example 1.

[0048] Changes in the first-stage distillation conditions: When the feed plates were changed from 14 to 40, the purity of isopropanol changed from 99.99% to 99.98% after distillation, and the heat load at the bottom of the tower did not change. When the reflux ratio was changed from 13 to 6, the purity of isopropanol changed from 99.99% to 99.98%, and the heat load at the bottom of the tower changed from 200kw to 108kw. Changes in the second-stage distillation conditions: When the feed plates were changed from 35 to 30, the purity of isopropanol changed from 99.98% after distillation, and the heat load at the bottom of the tower did not change. When the reflux ratio was changed from 8 to 4, the purity of isopropanol changed from 99.99% to 99.98%, and the heat load at the bottom of the tower changed from 24kw to 108kw.

[0049] It can be seen that the feed position has an impact on product purity, and the change in reflux ratio has a very obvious impact on product purity and tower energy consumption.

[0050] Example 5 The purification device in Example 1 was used to purify industrial-grade isopropanol. This example mainly illustrates the selection of resin types, and the other steps are consistent with Example 1.

[0051] The resin was replaced with LX-935 and LSD396. The filling method was that the upper filler was LX-935 and the lower filler was LSD396. The volume ratio of the upper and lower fillers was 1:3. When the working pressure of the resin tower was 2 bar and the working temperature was 25°C, after the resin cation exchange, the anion concentration in the isopropanol was controlled below 80ppb, and the single cation concentration was controlled below 90ppt.

[0052] It can be seen that the choice of resin has an important influence on the removal of anions and cations.

[0053] Example 6 The purification device in Example 1 was used to purify industrial-grade isopropanol. This example mainly illustrates the selection of filter types, and the other steps are consistent with Example 1.

[0054] It takes multiple stages of filtration to remove particles of different sizes from the material. The filtration device is divided into two sets, A and B. Each set is divided into three stages of filtration. There is pressure difference detection and display between each stage. The present embodiment is configured for circulating filtration including three-stage microporous folded filter elements of 100nm, 50nm, and 30nm in series filtration. The results of detecting particles in the material after filtration are: the concentration of particles greater than 0.2 microns is 33 particles / ml, the concentration of particles greater than 0.1 microns is 80 particles / ml, and the concentration of particles greater than 0.05 microns is 165 particles / ml, which is significantly greater than the previous embodiments.

[0055] The experimental results of Examples 2-6 are shown in the following table. The results in the table are representative results in each example. Although they cannot represent all possible results, they are representative of the overall trend. In addition, this patent cannot list all examples, and the results of other similar examples are equivalent to the protection scope of this patent.

[0056]

Claims

1. A method for producing ultra-high purity electronic grade isopropyl alcohol, characterized in that: The production steps include: (1) Dehydration of mixed packing: industrial grade isopropyl alcohol is passed through a mixed packing adsorption tower at a certain flow rate for dehydration; (2) Two-stage distillation: The dehydrated isopropanol enters the heavy removal tower and the light removal tower for cyclic distillation in turn, and the volatile components and metal salt heavy components are removed by separating the light and heavy components; (3) Online purity detection: purity analysis of the distilled material is performed. When the purity reaches 99.99% or above, the next step of impurity removal is carried out. Otherwise, the material is distilled again until the purity reaches 99.99% or above. (4) Resin filtration: The distilled isopropanol is further purified by ion exchange to remove anions and cations in the isopropanol; (5) Circulation filtration: The isopropanol after resin filtration is circulated and filtered to remove nano-sized particles in the isopropanol; (6) Secondary dehydration of mixed packing: The filtered resin is dehydrated again in the mixed packing to obtain G5 grade electronic grade isopropyl alcohol.

2. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: The mixed filler in step (1) is 3A molecular sieve, polyacrylic acid cross-linked resin, and acrylonitrile-vinyl acetate copolymer saponified resin; The filling method is as follows: the upper filler is acrylonitrile-vinyl acetate copolymer saponified resin, the middle filler is polyacrylic acid cross-linked resin, and the lower filler is 3A molecular sieve.

3. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: During the distillation process of the deweighting tower in step (2), the feed pressure is 3.0-5.0 bar, the feed is at room temperature, the reflux ratio is 13-20, the tower top pressure is 0.05-0.085 MPa, and the tower top extraction ratio is 0.8-1.5; During the distillation process of the light-removal tower, the feed pressure is 2.0-5.0 bar, the feed temperature is 80-85°C, the reflux ratio is 8-15, the tower top pressure is 1.8-3.5 bar, and the tower bottom extraction ratio is 0.7-1.

2.

4. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: In step (3), the purity analysis adopts a chromatographic detection method, and its detection conditions are as follows: chromatographic column: SH-Rtx-624, column temperature program: 40-150°C, 5-10°C / min, split injection, and the organic content of the isopropanol after distillation is detected. When its organic purity reaches 99.99% or more, proceed to the next step.

5. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: In step (4), the removal of anions and cations is carried out by exchange removal using mixed resins, the types of mixed resins are LX318 and ER80, and the filling method is that the upper layer filler is LX318 and the lower layer filler is ER80; When the working pressure of the resin tower is 2-5 bar and the working temperature is 25-30℃, the removal of anions and cations is achieved through the resin cation exchange.

6. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: The isopropanol after resin filtration in step (5) is then circulated and filtered, and the filtration is performed in series using microporous folded filter elements with pore sizes of 120-100 nm, 50-40 nm, and 10-5 nm.

7. The method for producing ultra-high purity electronic grade isopropyl alcohol according to claim 1, characterized in that: In step (6), the mixed filler is polyacrylic acid cross-linked resin and acrylonitrile-vinyl acetate copolymer saponified resin, and the filling method is that the upper layer filler is polyacrylic acid cross-linked resin and the lower layer filler is acrylonitrile-vinyl acetate copolymer saponified resin.

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